fuel issue at start

[sshanky]

Hi,

I recently replaced my fuel filter with a standard one from an auto parts store (it's clear with a circular paper element inside). Since then, there are issues starting cold. It starts quickly, but then loses fuel after a 1/2 second, and then I have to hold the starter for 3 to 5 seconds until fuel seems to reach the engine. Works after that, and if started while warm.

I suppose there must be a correlation with the new filter, but I can't seem to figure out what would cause that. Does the slightly larger chamber of the filter allow fuel to drain away from the area over time? Should I get the OEM style filter?

Thanks

[srwilson]

Did you find your problem?
Is it a carb or FI?

If carb'd and it's starting then dying then I'd say the float level is ok at start up however it's not being maintained or replaced quickly enough. That could mean that the fuel pressure is not keeping up or you could have a fuel leak in the supply line. The line would need to fill before it could supply the fuel to the carb. That is what it sounds like to me from your description; the additional cranking would refill the line.

Even a small leak at the filter will drain the line going to the carb if left sitting for a while. If you just replace the Filter that makes me even more suspicious of a leak.

Good Luck!!

[sshanky]

Thanks for your reply! If there is a leak, where are you thinking it might be? I don't think there is fuel underneath the car (there's oil of course ) but I do smell fuel often...would a leak small enough for just air be enough to cause this? Is there any reason to buy the right fuel filter, or should any one work? The car is 1969 and does have a weber carburetor. Thanks!

[srwilson]

I suspect a leak could be right at the fuel pump since it is the lowest point (I believe). Is your fuel filter right at the Fuel Pump? I know little about a 69, sorry. You should have two connections at the pump, an In and Out. Could be while installing the new filter you managed to crack the tubing or the tubing has come loose from either of the two points. You should be able to get your hand down there after you've shut it off and feel for the presence of gas.

The carb has a diaphragm that if cracked will cause the float bowl to empty while sitting, thus making it harder to start and increase cranking time to refill the bowl. This too can produce a raw gas smell. But from your description I would not suspect this to be your problem. Nevertheless, you might want to check it anyway.

If you are smelling raw fuel I think you can count on a leak somewhere unless your running super rich.

Yes, even a very small leak at the right spot (low and gravity fed) can empty the line.

Not sure about the original vs. aftermarket filters. I can't imagine that the original has some special feature that would prevent the issue you are having, however I can't say for sure.

[sshanky]

Thanks, very good info. I'm going to check it out now. The fuel filter is sort of loosely connected by a couple of hoses, one of which I had to replace, held by metal hose clamps. I haven't tried finding the pump, so I don't know where it is. I have an old manual somewhere so I'll find it. Thanks a lot... I'll report back.

[sshanky]

I noticed with the new filter the fuel level is dropping slowly, overnight it empties out. The old filter was metal and small -- could it have been a check valve?

[sshanky]

I went back to the auto parts store and they looked it up again, finding a different filter that is all metal with a ridge around the midline. It's just as large as the plastic clear one I had bought, just metal. I double checked the hose, replaced two pieces that were too large for the new filter (the filter requires a smaller hose than the car's fittings, but I just stretched the smaller hose onto the car's fittings easily). Same problem. After sitting for two days, the filter must've been completely empty, because i had to crank for 10 seconds before it started.

I'm thinking of using a smaller filter (that won't take as long to fill), or buying a check valve.

By the way, the fuel filter is between the fuel pump (on the engine block) and the carb, so it's right up there next to the engine. I have not looked underneath the car yet as I can't easily lift it right now, so I don't know if there is a filter under there or not.

[majicwrench]

Old "filter" could have been a check valve, yes. Do you still have it?? Smaller filter won't do you much good.
Factory fuel pump has check valve built in to it, but all it takes it a little debris and valve will leak back, thus some folks put check vavles in the line.
Keith

[sshanky]

I was afraid that it was a check valve...I don't know where it is! Might have tossed it.

Meanwhile, if that was a check valve, then there must be a fuel filter somewhere else on the car, no idea where.

Also, is it possible that there is a diaphragm or needle in the carburetor that is leaking vacuum?